\begin{table}[H]\centering \caption{Lane mile weighted means of network characteristics \label{tab:trends_table}}         \begin{tabular}{l*{4}{c}}\hline         
          &     1984&     1992&     2008\\
\hline
Urban (HPMS)&    30.23&    33.51&    42.74\\
Urban (NLCD)&    13.13&    13.20&    13.26\\
Grade (HPMS)&        .&     1.24&     1.06\\
Water (NLCD)&     7.26&     7.42&     7.51\\
Elevation&   456.19&   448.95&   440.08\\
\(\%\) New miles&     0.71&     0.51&     0.16\\
Structural Number   &        .&     6.63&     6.87\\
\(\%\) Flexible   &        .&    21.81&    24.28\\
\(\%\) rigid  &        .&    40.90&    26.83\\
\(\%\) composite  &        .&    37.28&    48.89\\
Unionization&    24.70&    20.09&    15.93\\
         \hline         \end{tabular} \end{table}
